Electric Current

The flow of electric charge is known as electric current. Electrons move through a conductor to carry electric current. Current electricity is the flow of electric charge, similar to how water flows in a river. It is the energy that powers electrical devices like bulbs, appliances, and the wiring in our homes.

1. Current (I): Current is defined as the amount of electric charge ($Q$) that flows through the cross-section of a conductor in unit time (t).

I=${\displaystyle \frac{\text{Q}}{\text{t}}}$

2. Electric circuit: An electric circuit is a continuous and closed path of an electric current.

3. Direction of Current: While electrons move from the negative terminal to the positive terminal of a cell, the conventional direction of current is considered opposite to this, flowing from the positive terminal to the negative terminal.

SI Unit of Electric Charge:

• The unit of charge in SI units is coulomb (C). Current is expressed in amperes (A). The charge of one electron is 1.6×10⁻¹⁹ C
• Ampere: A conductor flows one ampere of current if one coulomb charge passes through it every second. 1A=${\displaystyle \frac{\text{1C}}{\text{1s}}}$

Very small values of current are expressed in the following units:

• 1 mA (milliampere) = 10⁻³ A
• 1 μA (microampere) = 10⁻⁶ A

These smaller units are used when dealing with tiny currents, such as those in electronic circuits or devices like mobile phones and sensors.